Support is requested for a five-year ADAMHA Research Scientist Development Award, K02. The primary theme of the candidate's activities is to contribute to efforts to identify specific genetic loci that confer vulnerability to schizophrenia. The candidate is currently PI of an NIMH- funded study to screen the genome using a map of highly polymorphic DNA markers to identify a locus or loci linked to schizophrenia-related disorders in a sample of well-characterized multiplex families. Conceptual and methodological issues relevant to schizophrenia linkage studies are discussed, work to date is summarized, and progress toward collaboration is described. Additional planned areas of investigation include: study of schizophrenia in a more isolated population for future DNA association studies; the phenomenology of spectrum disorders in families of schizophrenic and affective probands; and dimensional approaches to classifying schizophrenic psychopathology.